Occurrence of a case of influenza A(H1N1)pdm09 and B co-infection during the epidemic season 2012–2013

We report the detection of one case of co-infection with influenza A(H₁N₁)pdm09 and B, occurred during the 2012–2013 influenza season in Sicily. The dual infection was identified in a 18-year-old boy, who was not covered by specific vaccination and who had no other pre-existing risk factors. He presented classical symptoms of influenza-like illness developing no respiratory complications. A(H₁N₁)pdm09 viral concentration was initially about 10-fold higher than B virus, whereas its clearance was more rapidly achieved than in the case of B virus infection. Although influenza co-infection appears to be a rare event, a continued influenza surveillance activity is recommended, in order to evaluate diversity and evolution, but also to support public health prevention measures.